1. Field of the Invention
Generally, the present disclosure relates to the field of integrated circuits, and, in particular, to integrated circuits wherein a damascene technique is employed for forming electrical connections between circuit elements.
2. Description of the Related Art
Integrated circuits include a number of individual circuit elements such as, for example, transistors, capacitors, diodes and resistors, which are interconnected by means of electrically conductive lines. The electrically conductive lines may be formed of metal including copper, such as substantially pure copper or a copper alloy. For forming the electrically conductive lines, damascene techniques may be employed.
In damascene techniques, trenches and contact vias are formed in an interlayer dielectric, which may include silicon dioxide and/or a low-k material having a smaller dielectric constant than silicon dioxide. In the trenches and contact vias, a diffusion barrier layer may be formed. After the formation of the diffusion barrier layer, the trenches and contact vias may be filled with the metal including copper. This may be done by means of electroplating for depositing the metal and chemical mechanical polishing for removing portions of the metal deposited outside the trenches and contact vias.
The diffusion barrier layer may help to substantially avoid or at least reduce a diffusion of copper from the metal into the interlayer dielectric and/or other portions of the semiconductor structure, which might adversely affect the functionality of the integrated circuit.
Issues that can occur in the above-described damascene process may include a formation of voids in the trenches and/or contact vias. The presence of voids in electrically conductive lines may increase the likelihood of electromigration occurring. Electromigration may further increase the size of voids, which may finally lead to a failure of the electrical connection provided by the electrically conductive lines.
Further issues that can occur in the above-described damascene process may include a relatively low adhesion between the diffusion barrier layer and the metal.
In view of the situation described above, the present disclosure provides methods which may allow a reduction of the likelihood of voids in contact vias and/or trenches filled with a metal occurring and/or wherein an improved adhesion between the metal and a diffusion barrier layer is provided. Moreover, the present disclosure provides devices having an improved adhesion between a metal in a contact via and/or trench and a diffusion barrier layer.